Process for preparing 2, 2&#39;-biaryldicarboxylic acids



United States Patent 6 PROCESS FOR PREPARING 2,2 -BIARYLDICAR- BOXYLIC ACIDS Philip S. Bailey, Austin, Tex assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware No Drawing. Application May 14, 1956 Serial No. 584,428

9 Claims. (Cl. 260-469) This invention is directed to a process for the preparation of 2,2'-biaryldicarboxylic acids. More particularly, the present invention is directed to a process for the preparation of 2,2-biaryldicarboxylic acids such as diphenic acid from ozonization products of phenanthrene compounds.

In application Ser. No. 584,461 of Philip S. Bailey, filed of even date herewith, there is disclosed a process for the preparation of 3,8-alkoxy-4,5,6,7-diaryl-1,7-dioxacyclooctanes (hereinafter referred to as dialkoxy peroxides) by the ozonization of phenanthrene compounds in suspension in C to C aliphatic alcohols, such dialkoxy peroxides having the formula:

wherein R is a C to C alkyl group.

It will be understood that when the dialkoxy peroxide is derived from phenanthrene the aryl groups of Formula I, supra, will-be unsubstituted, as shown. However, when the dialkoxy peroxide is derived from a substituted phenanthrene as hereinafter set forth, the aryl groups will be correspondingly substituted.

In accordance with the present invention, 2,2'-biaryldicarboxylic acids are prepared from such 3,8-dialkoxy peroxides by hydrolyzing such peroxide with a basic hydrolyzing agent and by oxidizing the hydrolysis product with an oxidizing agent, such hydrolysis and oxidation reactions being conducted either simultaneously or sequentially in solution in a non-reactive polar organic solvent. For satisfactory results it is necessary that the dialkoxy peroxide be substantially free from reaction byproducts formedduring the ozonization of the parent phenanthrene compound as described in the said copending application Serial No. 584,461.

While applicant does not wish to be bound by any particular theory, it is believed that the conversion of the dialkoxy peroxide to the dicarboxylic acid occurs in a stepwise manner with the formation of intermediate products. Thus, it is believed that, as a result of the hydrolysis reaction, the peroxide is first converted to an alkyl 2'-formyl-Z-biaryl-carboxylate which is, in turn, converted to a 2'-formyl-2-biarylcarboxylic acid. It is further believed that it is the 2-formyl-2-biarylcarboxylic acid which is oxidized to form the 2,2'-biarylcarboxylic acid. This may be represented schematically as follows:

2,870,194 Patented Jan. 20, 1959 r" o-o H 1% 0:0

r H 5 o-oR' .(J) O (II) (III) o=o o OOH p-orr 00 on 0 (IV) (V) In the above formulae R represents a C to C alkyl group. The above schematic showing has been made with respect to a dialkoxy peroxide derived from phenanthrene. It will be understood that in the case of dialkoxy peroxides derived from substituted phenanthrenes the aryl groups of the above formulae will be correspondingly substituted.

Hydrolysis of the dialkoxy peroxide (Formula II) to form an alkyl 2-formyl-2-biarylcarboxylate and hydrolysis of the carboxylate (Formula III) to form a 2'-formyl-2- biarylcarboxylic acid (Formula IV) should be conducted under non-acidic conditions if the desired products are to be obtained. Oxidation of 2'-formyl-2-biarylcarboxylic acid to form a 2,2-biaryldicarboxylic acid (Formula V) may be conducted under alkaline, neutral, or acidic conditions.

In accordance with one embodiment of the present invention the dialkoxy peroxide starting material is brought into simultaneous contact with a suitable basic hydrolyzing agent and with an oxidizing agent. In accordance with another embodiment of the present invention the peroxide starting material is first hydrolyzed (by either a one step or two step hydrolysis) and the 2'- formyl-Z-biarylcarboxylic acid hydrolysis product is then contacted with an oxidizing agent to form a 2,2-biaryldicarboxylic acid.

The hydrolysis and oxidation reactions, whether conducted simultaneously or sequentially, are preferably conducted at a temperature of at least about 60 C. and for best results the reactions are conducted at reflux temperature.

When the peroxide starting material is derived from phenanthrene, the dicarboxylic acid is diphenic acid. Diphenic acid and similar dicarboxylic acids, obtainable by the process of the present invention are useful for a wide variety of purposes. They may be used, for example, as intermediates in the preparation of plasticizers and, in the form of their anhydrides, for the preparation of polyamides, polyesters, etc.

There is used as a starting material for the present invention the isolated 3,8-alkoxy-4,5,6,7-diaryl-1,7-dioxacyclooctane reaction product formed by the ozonization of a phenanthrene compound in a C to C aliphatic alcohol as described in the aforesaid application Serial No. 584,461. Mixtures of two or more such dialkoxy peroxides may be used, if desired.

Thus, there may be used peroxides derived from phenanthrene and substituted phenanthrenes. Representative substituted phenanthrenes from which the peroxides may be derived include retene' (1-methyl-7-isopropyl-phenanthrene), 3-methylphenanthrene, l-methylphenanthrene, 2-

ivention may A preferred class of phenanthrene compounds from which the peroxide starting materials for the present inbe derived include phenanthrenes having the formula: (V R wherein R is selected from the group consisting of hydrogen and alkyl and aryl groups.

In this situation, the dialkoxy peroxide will have the formula:

(VII) R il R C-O H l H R (i-O V wherein R has the meaning given above with respect to Formula VI; and wherein R is a C to C alkyl group.

The p lar organic solvent to be employed may be an alcohol, ketone, ether, etc., or a mixture of two or more such solvents which are miscible with each other. Representative solvents of this nature include C, to C aliphatic alcohols such as methanol, ethanol, propanol, butanol, amyl alcohol, hexyl alcohol, heptyl alcohol, octanol, nonyl alcohol; ketones such as acetone, methylethylketone, diethylketone, methylpropylketone, methylisopropylketone, cyclohexanone, etc.; ethers such as diethyl ether,

, a two step hydrolysis reaction is to be employed wherein the first intermediate product obtained is an alkyl-2'- formyl-Z-biphenylcarboxylate, any suitable polar organic solvent of the type set forth above may be used in the prepartion of the carboxylate. Furthermore, in this instance, the carboxylate may be formed merely by heating the peroxide starting material in solution in the polar organic solvent to a temperature of more than about 60 u C. That is to say, it is not absolutely necessary to employ a hydrolyzing agent when converting the peroxide starting material to a carboxylate.

when the peroxide"'startingmaterial is'to be directly hydrolyzed to a 2'-formyl-2-biarylcarboxylic acid or when the alkyl carboxylate is to be formed as an intermediate to be hydrolzed to such acid, it is necessary to employ a hydrolyzing agent. In this situation, the polar organic solvent to be employed should be miscible with the hydroly'zing agent. The hydrolyzing agents of the present invention are, in general, miscible with alcohols, ketones, etc., such asC to C aliphatic alcoh'ols, ace- K, tone, cyclohexanone,- methylethylketone, diethylketone,

methylpropyllsetone, methylisopropylketone, etc.

In situations wherein simultaneous hydrolysis and oxidation is accomplished, or whenthe 2-formylbiarylcarboxylic acid is oxidized, it is necessary to employ a solvent such as an alcohol; ketone," etc. which is not reactive with the oxidizing agent. In this situation, of

course, the strength of the oxidizing agent will be significant with resp ect to the solvent to be employed.

indicated, the dialkoxy peroxide starting material is contacted in solution in a polar organic solvent with a suitable hydrolyzing agent in order to form the dialdehyde.

A wide variety of basic hydrolyzing agents may be used. Thus, there may be used solutions of alkali metal hydroxides, suspensions of atleast partially water soluble alkaline earth metal hydroxides, aqueous solutions of water soluble amines, ammonium hydroxide, etc. For example, there may be used aqueous solutions of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, eto; aqueous slurries of calcium hydroxide, barium hydroxide, etc. Among the amines that may be used in aqueous solution are primary, secondary and tertiary amines such as pyridine, triethylamine, diethylamine, ethylamine, piperidine, morpholine, etc. Ammonium hydroxide may also be used if desired, The amount of hydrolyzing agent to be employed should be at least the chemical equivalent of the dialkoxy peroxide. Mixtures of two or more suitable basic hydrolyzing agents may be used, if desired.

Any suitable oxidizing agent may be used for the oxidization reaction such as hydrogen peroxide, silver oxide, Tollens reagent (silver ammonia hydroxide or silver ammonia salts), Fehlings solution, Benedicts solution and other similar cupric complex oxidizing agents; ferric chloride or nitrate or sulfate; potassiumpterricyanide;

sodium peroxide; barium peroxide; etc. Suitablemixtures of two or more such oxidizing'agentsmay alsobe used, if desired.

In situations wherein a non-alcoholic polar" organic solvent is employed, there may be used oxidizing'agents such as potassium permanganate, potassium dichromate (under acidic or neutral conditionsonly), chromic'acid,

nitric acids, or Caros acid.

Further, in situations wherein sequential hydrolysis and oxidation are employed to provide, as an intermediate,

either an alkyl 2-tormyl-Z-biaryl-carboxylate or a 2 formyl-Z-biarylcarboxylic acid, it is possible to utilize an ozone-containing ga's under anhydrous conditions in "1,2-dioxacyclooctane, about 5 ml. of

' ethyl alcohol.

oxidizingsuch intermediate in order to form the desired 2,2-biaryldicarboxylic acid.

The invention'will be further illustrated by the following specific examples which are given by way of illustration and'n'o't as limitations on the scope of this invention.

Exdmple I Add about 1 gram of 3,8-dimethoxy-4,5,6,7dibenzoa 30%"aqueous solution of hydrogen peroxide and about 20 ml. of a aqueous solution of sodium hydroxide'to about 30 ml. of

Heat the resultant n 'iixture to reflux temperature and reflux the same for about 30 minutes. At

the end or this time acidity the solution witli'di1ut'h drochloric acid and add abou t an equal volume of water thereto, Cool the resultant mixture. About an 84% .p'erature. I I I ftrrm'yl-Z-b'iphenylcarboxylate is obtained as in the case yield of crystalline diphenic acid (M. P. 216 222 C.) is obtained.- I

When 3,8-dimethoxy-4,5-(3-methylbenzo)-6,7?(4-isopropylbenzo)-l,2-dioxacyclooctane is substituted for the 3,8-dimethoxy-4,5,6,7-dibenzo-1,2-dioxacyclooctane and Example I is otherwise repeated, there is obtained as a product 3-methyl-4-isopropyl-2,2'-biphenyldicarboxylic acid, such acid having the formula:

(VIII) In like manner, there may be used. as a starting ma terial for Example I' an equivalent amount of'3,8-dimethoxy 4,5-benzo-6,7-(5-methylbenzo)-1,2-dioxacyclooctane, and'in this situationwhen Example I is otherwise repeated the product that is obtained ,is S-methyl- 2,2'-biphenyldicarboxylic acid, such acid having the formula: (I

C 0 OH "Example 11 Add about 0.5 gram; of 3,8-dimethoxy-4,5,6,7-dibenzo-l,2-dioxacyclooctane to about ml. of methanol and reflux the same for about '2 hours. 'At the end of this time dilute the reaction; product with about an equal volume of water and cool the resultant mixture to room temperature. There is obtained about a 93% yield of 'rnethyl-Z'-formyl-2-biphenylcarboxylate having theformula:

The biphenylcarboxylate gives a negative active oxygen test with potassium iodide and forms an oxime on reaction with hydroxylamine in the presence of pyridine. The analysis is as follows:

'Calcd. for C H O C, 74.99; H, 5.03.;.Found: C, 75.11, 75.06; H, 4.95, 4.93. 1 r

Example Add about 0.5 gram of 3,8-dimethoxy-4,5,6,7-dibenzo- 1,2-dioxacyclooctane and about 6 ml. of pyridine to about 10 ml. of ethanol and reflux theresultant reaction-mixture for about 30 minutes to 1 houri Dilute the fpr oduct with anequal' volume of Water and cool to room tem- Substantially the same yield of "rne'thyl-T- of Example II.

. Example I? Add about 2 grams of methyl.'2=formyl2-biphenylcarboxylate and about 10 ml. of a 10% aqueous solution of sodium hydroxide to about ml. of ethanol and reflux the resultant mixture for about 15 minutes. At t the end of this time acidify thereaction mixture with dilute hydrochloric acid and then dilute the acidified mix ture with about an equal volume of water. On cooling to room temperature there is obtained about an 80% yield of 2'-formyl-Z-biphenylcarboxylic acid (M. P. 134-135 C.) having the formula:

The compound gives a negative active oxygen test with potassium bromide, is soluble in dilute sodium hydroxide and sodium carbonate solutions and gives an infrared spectrum showing the presence 'or an aldehyde and/or carboxyl group. The analysis is as follows:

Calcd. for C H O C, 74.33; H, 4.46. Found: C, 74.13; H, 4.45.

Example V Add about 1 gram of 2'-formyl-2-biphenylcarboxylic acid, about 5 ml. of a 30% aqueous solution of hydrogen peroxide and about 20 ml. of a 10% aqueous solution of sodium hydroxide to about 30 ml. of ethanol and reflux the resultant mixture for about 30' minutes. At the end of this time acidify with dilute hydrochloric acid, dilute with about an equal volume of water and cool to room temperature. There is obtained, as a precipitate, about a yield of diphenic acid (M. P. 223-228 C.).

' Example VII Dissolve about 1.1 grams of 2-formyl-2-biphenylcar boxylic acid in about 15 ml. of methanol and cool the resultant solution to about 0 C. Pass -a mixture of ozone and oxygen containing 4 Weight percentof ozone through the cooled solution until the absorption of ozone ceases. Slightly in excess of about 1 mol of ozone per mol of 2- formyl-2-biphenylcarboxylic acid is absorbed. Partially evaporate the methanol and then add water to form a precip)itate. The product is diphenic acid (M. P. 216222 What is claimed'is: v

1. A process which comprises the steps of heating to a temperature of atleast about 603C. in solution in a C to C aliphatic alcohol under non-acidic conditions a cornpound having the formula:

7 and recovering frornthe. resultant reactionmixturea first nterm d a sih v ns ths iq l s v andoxidizing said second intermediate with an oxidizing agent in solution in a non-reactive polar organic solvent; whereby there is obtained a product having the formula:

R in the above formulae being selected from the group consisting of hydrogen and alkyl and aryl groups; and R--in the aboveformulae beingaC to.-C alkyl group.

,' '2.A process conducted at a temperature of at least about 60-C. which comprises the steps of heating 3,8-

dimethoxy-4,5,6,7-dibenzo-1 2-dioxacyclooctane in .solution in a Qyto C aliphatic alcoholand recovering methyl formyl-2- biphenylc'arboxylate from the resultant reaction produet hydroly zing the methyl Z'JormyI-Z-biphenylcarboxylate;in'solution'-in a C 'to C .alipha'tiealcohol, recovering 2'-formyl2-biphenylcarboxylic acid frornI-the reaction product and oxidizing said 2'-formyl-2-biphenylcarboxylic acid in solution in a C tohC aliphatic alcohol s whereby diphenic acid isobtained. r

3. A process tor-preparing a compound vhaving the formula? 8 which comprises the step of "heating of at least about C. in solution in a C alcohol; a'compound having the formula; R V

R in the above formulae being selected from the group consisting of hydrogen and alkyl and aryl groups; and R in the above formulae being a C to C alkyl radical.

4. A process for preparing a 2,2-biaryldicarboxylic acid which comprises the steps of dissolving a feed material consisting essentially of a 3,8-alkoxy-4,5,6,7-diaryll,7 dioxacyclooctane. in a. non-reactive polar organic solvent. and hydrolyzing said dioxacyclooctane in said solutionunder, non-acidic conditions to convert said dioxacyclooctane to the corresponding alkyl 2-formylbiarylcarboxylate andloxidizing said 2-formyl-biarylcarboxylate infsaid solution, said hydrolysis and oxidation reactions being conducted at a temperature intermediate about 60 C. and refiux temperature, acidifying the reaction mixture and then recovering said dicarboxylic acid, said solvent being selected from the class consisting of aliphatic alcohols, ketones and ethers.

5. A method as in claim 4 wherein the dioxacyclooctane is a compound having the formula:

. R wherein R is selected from the class consisting of g'eriQC we; alkyl, and phenyl; and wherein R to C alkyl group.

6. A method as in claim 5 wherein said dioxacyclooctane is simultaneously reacted with a hydrolyzing agent and an oxidizing agent under basic conditions.

7. A method as in claim 4 wherein the dioxacyclooctane is 3,8-dimethoxy-4,5,6,7-dibenzo-1,2-dioxacyclooctane and wherein the solvent is a C to C aliphatic alcohol.

8. A process for preparing methyl 2-formyl-2-biphenylcarboxylate which comprises the step of refluxing a methanol solution of 3,8rdimethoxy-4,5,6,7-dibenzo-1,2-dioxacyclooctan'e under non-acidic conditions.

' 9. A process for preparing 2-formyl-2-biphenylcarboxylic acid which comprises refluxing a solution ofi3,8- dimetlioxy-4,5,6,7-dibenzo-1,2-dioxacyclooctane in methanol in the presence of a basic hydrolyzing agent.

hydrois a C References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES O'Connor et al.: Ind. and Eng. Chem., vol. 49, No. 10, pp. 1701--1702',r0ctober 1957'.

at a temperature to: C aliphatic 1 

8. A PROCESS FOR PREPARING METHYL 2''-FORMYL-2-BIPHENYLCARBOXYLATE WHICH COMPRISES THE STEP OF REFLUXING A METHANOL SOLUTION OF 3,8-DIMETHOXY-4,5,6,7-DIBENZO-1,2-DIOXACYCLOOCTANE UNDER NON-ACIDIC CONDITIONS. 